NEWS |
Brenner Tunnel main bores finish on Italian side
Blasting starts to create Potomac River Tunnel shafts US - Underground blasting to create launch shafts for two 6.4m-diameter TBMs began on DC Water’s 8.9km-long tunnel Potomac River Tunnel in early May. Excavations on the 31.4m-deep shafts are to be finished in February 2026. TBM - ‘Mary’ - is to excavate north, boring
through rock to the endpoint of the tunnel at Georgetown University’s entrance on Canal Road Northwest. The other machine - TBM ‘Emily’ - is to
bore south to the Joint-Base Anacostia Bolling (JBAB) site, where the Potomac River Tunnel connects with the Anacostia River Tunnel. TBM ‘Mary’ recently passed its Factory
Above: The breakthrough by TBM Flavia marked completion of excavation on the Italian side of the Brenner Base Tunnel PHOTO CREDIT: BBT SE
ITALY - Excavation work on the Italian side of the bi-national Brenner Base Tunnel project has been completed. TBM ‘Flavia’, the last of three
TBMs operated by the Webuild- led consortium for the H61 Mauls section, recently finished the excavation of the west main tunnel on the Italian side of the Alpine high-speed rail project, being built with Austria. The 10.71m-diameter TBM was
launched in April 2019 and bored for the Mules 2-3 lot, reaching the border with Austria. The machine installed 65,000 segments along the 14.3km-long portion of the base tunnel. During the long tunnelling work,
though, there was a challenge for the TBM caused by high overburden and local weak rock two years ago. In April 2023, the machine came
to a standstill for several months, 3.5km from the Brenner Pass, because of overburden of more than 1,200m above the tunnel and the low strength of the fractured rock. After several attempts, the TBM was then restarted. While ‘Flavia’ has constructed the
west main tunnel on the Italian side, the east tunnel was built by another TBM - ‘Virginia’ - which completed its journey in March 2023. Tunnel boring on the Italian
side of the joint project also saw excavations before the main tunnels.
6 | July 2025
TBM ‘Serena’ excavated a large part of the exploratory tunnel and reached its destination in November 2021. With the most recent TBM finish
on the Italian side, overall progress on Lot Mules 2-3 now stands at more than 95%. The Mules 2-3 Lot represents the
main section of the Italian side of the tunnel. It involves the excavation of a system of 65km of tunnels, about two-thirds of which (more than 40km) were constructed using TBMs.
BBT SE board members Gilberto
Cardola and Martin Gradnitzer acknowledged the tunnelling team’s work. “With the arrival of TBM ‘Flavia’,
the mechanised tunnelling on the Italian side has been successfully completed,” they said in a statement. They added: “Sincere thanks
also go to the planners, engineers, geologists, and all BBT SE employees involved in the construction, whose valuable contributions made a significant contribution to achieving this important milestone.” Webuild is working on a few
lots of the Brenner Base Tunnel, including Isarco Underpass which marks the southernmost point of the tunnel, on the Italian side, before the project link reaches Fortezza station.
Acceptance Test (FAT), in Germany, and is to be at the West Potomac Park site in autumn this year. The second TBM is to be delivered to site in 2026. Potomac River Tunnel is the next major
phase of DC Water’s Clean Rivers Project to reduce the sewer overflows and help to improve the water quality of the Potomac River and, ultimately, Chesapeake Bay. The project consists of the large-
diameter, deep sewer tunnel as well as diversion facilities, drop shafts, and support structures. The tunnel system will capture the
combined overflow of wastewater and stormwater during major weather events.
J Gallagher wins Bahrain microtunnel sewer job BAHRAIN - Joseph Gallagher has been awarded the microtunnelling sub-contract for the Sheikh Isa Bin Salman Trunk Sewer (SIBS) project in Bahrain. The contract was awarded by Haji
Hassan Group. The project involves the installation of
nearly 10km of new sewer tunnel, with diameters ranging from DN1200 to DN1800. The works, to be delivered over a
15-month programme, are to enhance wastewater capacity and resilience in the region, forming part of Bahrain’s broader infrastructure investment strategy. This latest contract follows the delivery
of the Zinj Trunk Sewer project in 2023, where Joseph Gallagher installed critical sewer infrastructure, again with Haji Hassan Group. “We look forward to delivering another
key project together and supporting Bahrain’s infrastructure plans for the future,” said Joseph Gallagher director Steve Gallagher.
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